diff --git a/toolchain/check/impl.cpp b/toolchain/check/impl.cpp
index d086fa361c855..ec9259c6bd12c 100644
--- a/toolchain/check/impl.cpp
+++ b/toolchain/check/impl.cpp
@@ -315,7 +315,8 @@ auto AddConstantsToImplWitnessFromConstraint(Context& context,
   }
 
   // For each non-function associated constant, update witness entry.
-  for (auto [index, decl_id] : llvm::enumerate(assoc_entities)) {
+  for (auto index : llvm::seq(assoc_entities.size())) {
+    auto decl_id = assoc_entities[index];
     decl_id =
         context.constant_values().GetInstId(SemIR::GetConstantValueInSpecific(
             context.sem_ir(), interface_type->specific_id, decl_id));
diff --git a/toolchain/check/testdata/impl/fail_todo_use_assoc_const.carbon b/toolchain/check/testdata/impl/fail_todo_use_assoc_const.carbon
index d46d76029c647..45cbfa705c980 100644
--- a/toolchain/check/testdata/impl/fail_todo_use_assoc_const.carbon
+++ b/toolchain/check/testdata/impl/fail_todo_use_assoc_const.carbon
@@ -479,7 +479,7 @@ impl () as I where .N = 2 {
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import = import Core
 // CHECK:STDOUT:   %I.decl: type = interface_decl @I [template = constants.%I.type] {} {}
-// CHECK:STDOUT:   impl_decl @impl.43 [template] {} {
+// CHECK:STDOUT:   impl_decl @impl.44 [template] {} {
 // CHECK:STDOUT:     %.loc14_7.1: %empty_tuple.type = tuple_literal ()
 // CHECK:STDOUT:     %.loc14_7.2: type = converted %.loc14_7.1, constants.%empty_tuple.type [template = constants.%empty_tuple.type]
 // CHECK:STDOUT:     %I.ref: type = name_ref I, file.%I.decl [template = constants.%I.type]
@@ -537,7 +537,7 @@ impl () as I where .N = 2 {
 // CHECK:STDOUT:   witness = (%N, %F.decl)
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: impl @impl.43: %.loc14_7.2 as %.loc14_14 {
+// CHECK:STDOUT: impl @impl.44: %.loc14_7.2 as %.loc14_14 {
 // CHECK:STDOUT:   %F.decl: %F.type.936 = fn_decl @F.2 [template = constants.%F.6b2] {
 // CHECK:STDOUT:     %self.patt: %empty_tuple.type = binding_pattern self
 // CHECK:STDOUT:     %self.param_patt: %empty_tuple.type = value_param_pattern %self.patt, runtime_param0
@@ -550,7 +550,7 @@ impl () as I where .N = 2 {
 // CHECK:STDOUT:     %.loc15_26.2: type = converted %bool.make_type, %.loc15_26.1 [template = bool]
 // CHECK:STDOUT:     %array_type: type = array_type %int_2, bool [template = constants.%array_type]
 // CHECK:STDOUT:     %self.param: %empty_tuple.type = value_param runtime_param0
-// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.43.%.loc14_7.2 [template = constants.%empty_tuple.type]
+// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.44.%.loc14_7.2 [template = constants.%empty_tuple.type]
 // CHECK:STDOUT:     %self: %empty_tuple.type = bind_name self, %self.param
 // CHECK:STDOUT:     %return.param: ref %array_type = out_param runtime_param1
 // CHECK:STDOUT:     %return: ref %array_type = return_slot %return.param